Electric plug



, M. KAPLAN ELECTRIC PLUG Feb. 7, 1950 Filed March 20, '1946 FIG. 6

Patented Feb. 7, i950 r. UNITED STATES PATENT OFFICE ELECTRIC PLUG Morris Kaplan, Chicago, Ill.

Application March 20, 1946, Serial No. 655,678

3 Claims.

The present invention relates to electrical connectors, and more particularly to those of'the plug-in type.

It is an object of the present invention to provide a plug-in connector which may be utilized with sockets of the type used on automobile dashboards, such as cigarette lighter sockets, for instance. By the use of such a plug electrical connection may be made from the socket to some electrical instrument, such as a portable trouble light, for instance.

- It is a further object of the invention to provide such a plug connector which is compact, is easily assembled, is sturdy, and which operates satisfactorily.

It is a still further object of the invention to provide a plug connector which may be used in combination with standard sockets. V

The attainment of the above and further objects of the present invention will be apparent from the following specification taken in conjunction with the accompanying drawing forming a partthereof.

In the drawing:

Figure 1 is a longitudinal sectional view of the plug embodying the invention, shown in combination with a socket with which it is utilized;

Figure 2 is an end view of the plug shown in Figizire 1,looking in-the direction of the lines V 1 Figure 3 is a front view, disassembled, of one of the elements of the plug;

Figure 4 is a front view, disassembled, on an insulation element of the plug; Figure 5 is a side view of Figure 4, looking in the direction of the lines 5-5; "Figure 6 is a front view, disassembled, of another element forming part of the plug; and

I Figure 7 is a front View, disassembled, of one of the electrical connector members.

it is deemed advisable first to describe, briefly, a conventional automobile cigarette lighter socket with which it is utilizedin combination. The socket comprises an outer metallic casing l I havmember which is screw threaded at I! is secured thereto, the screw internally threaded sleeve 11 threaded on the post 13. The cap l6 extends forwardly, when tightened in place, until its front edge engages the rearward end of the plastic cylinder M.

A threaded terminal screw 18 extends within the central opening of the post l3, separated therefrom by an insulator tube l9, and terminates in a headed portion to which is secured three uniformly spaced metallic spring clips 2|, extending forwardly in the casing II, A metal clip 22 having outwardly extending lugs surrounds the screw IB with the lugs entering depressions in a plastic insulator 23, thus insuring against movement ofthe elements. The insulator 23 prevents the spring clips 2| from engagingthe casing II. An insulation washer prevents the clips 22 from engaging the post 13. It should go be noted that the cut-out portions 42in the eas- 25 the post l3,by an insulating washer 21.

. .40 In describing the plug embodying the invention ing three circumferentially spaced cut-out porspring lug I5 which extends a short distance within the casing II, for a purpose to be described hereinafter. A plastic cap or cylinder [4 surrounds the casing H at the forward, or right (Fig. '1) endthereoh A metal can l6; having a ing H are adjacentthe spring clipsj 2|, so that the latter cannot engage the casingfll.

' A nut 26 engages the screw threaded extremity 10f the screw l8 and is separated from the end of The: screw 18 receives the end terminal of a conductor leading from a suitable current source, The current will thus be conducted through the screw IE to the head thereof and to the spring clips 2%. 'Only one terminal is necessary as the electrical circuit may be completed-throughgrounding at some convenient point. f

The plug connector embodying the invention comprises a plastic handle 3| having a central opening and a screw threaded extremity 32. A plastic cylinder 33, internally threaded, engages the threaded portion 32. An electrical extension cord 34 extendsthrough the central opening of the handle 3! to some external operating unit, such as aportable trouble light. 7

A metallic grounding cap 36 is screw threaded into the connecting cylinder 33. The cap 36 may be seen more clearly in Figure 3, which is a View showing the cap 36, looking at the side opposite from the threaded portion. The cap 36 has a central opening 31 and two arcuate slots 38. When in proper position the cap 36 engages the 'short spring lugs I5 of the casing I I.

. .An insulation member 39, seen more clearly in Figures 4 and 5, also having a central opening and arcuate slots or troughs 4|, is so shapedas to engage the cap 36 with the slots 38 and the troughs 4| aligning. Such alignment is achieved through arcuate shoulder portions 40 on one side 7- memb w ich fillq ldq f. M ter:

away from the member 39.

A large-headed threaded bolt 41 extends.

through the central openings in the metallic cap 36, the insulation member 39, and the metallic end cap 43, a nut 48 engaging the threaded portion. An L-shaped electrical connector lug 49,

i extension cord, a metallic grounding cap having seen more clearly in Figure '7, and'likewise having a central opening to receive the bolt 41, is positioned between the nut 48 and the metallic cap 36, One of the terminals of the cord34 is..secured by suitable means, such as soldering, to an extending prong of the connector 49.

. As previously mentioned, the insulation member 39 engages the cap 36 and separates it from the metallic end cap 43." An insulation tube 5| surrounds the shank of they bolt 41 and extends through the central openings of the cap 36, the member 39, and the end cap 43.

A second electrical connector lug 52 having a central opening to receive the bolt 41. is positioned in engagement with the end cap 43 on the side The insulator 5| extends within thecentral opening of the connector, 52 also, thus preventing it from engaging arcuate slots 45 of the end cap 43 and through a rectangular slot 42 of the insulation member 39, and through one of the arcuate slots 38 of the cap 36. ,The second Wire of the cord 34 is secured to the prong in any convenient manner,

as by soldering. An electrical circuit may thus. be jextendedfromcthe'. prong '54 of the connector 52,,t0 the end cap .3,...withwhich it is in engagement. As the arcuate shoulders 4B of .theinsul'at ing member 3}} enter the slots 380i the cap 36, andasthe prong 54 passesthrough the rectangular slot 42, it is impossible for the prong. t short circuit against the cap 36.

The positioning of the various members and the tightening'of the bolt 48 on the bolt 41 will insure that the parts will be held firmly in place. When the plug is inserted in the socket, initially described, battery potential is thus extended from the socket spring clips 2 I, through the lip or overhanging portion 44 'oithe end cap 43 which engages them,"through the end cap 43, through the electrical connector 52 with which it is in to one terminal of the cord 34. It is to be remembered that the current source engagement, and over, the connector 'prong 54 had only one terminal, the circuit being cona central opening therein and opposed arcuate slots therein, means to connect said handle and said grounding cap, an insulating member having arcuate troughs extending part way therethrough, small rectangular slots extending all the way therethrough, and arcuate shoulder portions adjacent said grounding cap, said shoulder portionsextending within the arcuate slots in said grounding cap, an end cap having arcuate slots adjacent said' insulating member, an electrical connector for joiningone terminal of saidexten sion cord to said metallic grounding cap, a second electrical connector for joining the second terminal of said extension cord to said end cap, said second connector extending through an arcuate slot in said metallic grounding cap, the small rectangular-slot in said insulating member, and the arcuate 'slot'in' said end cap, and means to fasten said metallic grounding cap, said insulating member and said end cap together in sucha manner whereby said metallic grounding cap and said end cap will not be short circuited. f

2. In a plug connector, a handle ofinsulating material having a central opening to receive an extension cord, a metallic grounding cap having a central opening therein and opposed arcuate slots therein, means to connect said handle and said cap, an insulating member having arcuate troughs extending part Way therethrough, small rectangular slots extending all the Way there;- through, a central opening extending therethrough and also arcuate shoulder portionsadjacent said cap, said shoulder portions extending within the arcuate troughs in said cap, an end cap having arcuate slots adjacent said insulating member, an electrical connector for joining one terminal of said extension cord to said metallic grounding cap a second electrical connector for joining the second terminal of said extension cord to said end cap, said second connector being in contact with the end cap and having a portion extending through an arcuate slot in said metallic grounding cap, through the small rectangular slot in said insulating member, and through the arcuate slot in said end cap, and means to \fasten said metallic grounding cap, said insulating member and said end cap together in such a manner whereby said grounding cap and said end cap will not be short circuited, said means comprising an insulating tube and bolt means extending through the tube. 3.. In combination with an electrical socke having spring clips to which current is extended and a casing which is grounded, a plug connector comprising a handle of insulating material having'a central opening for receiving an extension cord, ametallic grounding cap of sufl'icient diam eter to engage said casing of said socket, a cylinder of insulating material for connecting said grounding cap and said'handle, an electrical connector for joining one of the terminals of said ex: tension cord to said grounding cap whereby said terminal is grounded, an insulating member overlying said grounding cap, a metallic end cap overlying said insulating member, a second electric connector in contact with the end cap, said metallic grounding cap and said insulating member and said second connector and said end cap having aligned central openings therethrough, an insulating tube extending through said openings, bolt means extending through said tube and securing the insulating member, the end cap and the second electric connector to the metallic grounding cap While the end cap is insulated from the metallic grounding cap, said second electric connector having a prong extending through the metallic grounding cap but insulated therefrom by said overlying insulating member, said end cap being of sufficient diameter to engage said REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,703,279 Meuer Feb. 26, 1929 2,276,867 Pistey Mar. 17, 1942 

